Acute myeloid leukemia (AML) is a collection of neoplasms with heterogeneous pathophysiology, genetics and prognosis. Based on cytogenetics and molecular analysis, AML patients are presently classified into groups or subsets of AML with markedly contrasting prognosis. For instance, the genetic translocations inv(16), t(8;21) and t(15;17) characterize AML with a relatively favorable prognosis, whereas the cytogenetically bad-risk leukemia's include patients with abnormalities involving 11q23, loss of 5(q) or 7(q), t(6;9) and t(9;22) (Löwenberg et al., 1999).
The most common molecular abnormality in AML is the internal tandem duplication (ITD) in the fms-like tyrosine kinase-3 gene (FLT3), a hematopoietic growth factor receptor (Levis & Small, 2003). FLT3 ITD mutations confer a bad prognosis to AML patients (Levis & Small, 2003). AML patients with mutations in the transcription factor cEBPa have been associated with good outcome (Preudhomme et al., 2002; van Waalwijk van Doorn-Khosrovani et al., 2003), while elevated expression of the transcription factor EVI1 predicts for notoriously poor survival (van Waalwijk van Doorn-Khosrovani et al., 2003). These examples of novel molecular prognostic markers underscore the importance of an extension of molecular analyses in AML.
Approximately thirty percent of all patients with acute myeloid leukemia (AML) are currently classified based on specific abnormal karyotypes in groups with either good or bad prognosis. The remaining seventy percent of patients, however, are not classifiable because of the lack of cytogenetic markers.
One of the aims of the present invention is to provide more accurate risk assessment tools for the diagnosis of AML. It is another aim to classify AML patients in which specific abnormal karyotypes have not been found and to distinguish these groups not only from the molecularly well-defined AML classes, but also to define prognostic subgroups within these unclassified AML types. The presence of additional prognostic classes in AML, not recognizable with currently available methods, may provide important insights into their pathophysiology. Therefore, it is an aim of the present invention to provide a more complete way of prognostication to patients with AML.